Patent GB-990255-A (GB)
Title: Sensing mechanisms for automatic vending machines
Inventor: GOALBY BARRY BIRCH
IPC: G07F7/00
Filed: 1962-03-26
Abstract: 990, 255. Radiation sensitive devices. THOMAS DE LA RUE & CO. Ltd. March 15, 1963 [March 26, 1962; May 8, 1962], Nos. 11441/62 and 17697/62. Heading G1A. [Also in Division G4] Tokens containing a radio-active isotope or element are sensed by a device to actuate the delivery mechanism of an automatic vending machine such as may be used for the sale of petrol or motor spirit. The tokens are cut from a sheet built up of layers of kraft paper impregnated with phenol-formaldehyde resin and cured, one or both sides being overlaid with a sheet of alpha-cellulose paper impregnated with a melamine formaldehyde resin containing a soluble compound of carbon 14 or uranium. The sheet is consolidated by heating under pressure between flat metal plates. The sensing device for the tokens is shown in Fig. 1 where insertion of a token in the slot 3 of a horizontally disposed channel operates contacts of microswitch MS. A solenoid M1 propels the token into a vertical shoot 1 where it is held, by a stop 10 projected by solenoid M2, for inspection by two Geiger-Muller tubes GM1, GM2-S. If during a timed interval the activity of the token is found to be acceptable a deflector 12 is taken out of the path of the token to allow it to be cashed through an exit F when it is released by the stop 10. If not acceptable the deflector stays in position and the token is rejected along a path E. The control circuit is shown in Fig. 3 where a token 13 is in position between Geiger-Muller tubes GM1 and GM2-S. The response of GM-1 is amplified at A1 to control relays L1 and S1, L1 operating at a first current threshold and S1 operating at a higher threshold. If the time during which L1 is operated and S1 is not operated coincides within limits with the time to be expected in response to a valid token, a relay M is operated to free the vending machine. The comparison may be made with a further Geiger- Muller tube exposed to a standard token, but as shown, the time of response is acceptable if it falls within the interval between the release of a relay S4 and the release of a relay L3. Relays L3 and S4 respond when switch MS (contacts A and B) is operated by the insertion of a token. Solenoids M1, M2, M3 energize to inject the token while blocking the token slot, position the stop 10, and withdraw the deflector 12. Relays L3 and S4 are energized by way of triode V which conducts for as long as capacitor C1 takes to discharge. After a period of time which should be sufficient for a valid token held on the stop 10 to have produced a response in GM-1 sufficient to operate relay L1 but not S1, relay S4 falls back and a circuit is completed to relay M to free the machine. If the token is spurious and produces too low a response, L1 will not operate during the interval in which S4 has released and L3 is releasing so that M is not energized. The final release of L3 released solenoids M1, M2, and M3 and the token is rejected. If the token is spurious and produces too high a response relay S1 will operate before relay S4 releases and prevents the energization of relay M with the same result. Where the token is valid, however, M operates and when L3 falls back solenoid M2 is disconnected to release the token which falls without hindrance from the deflector 12 since M3 remains energized over M. Solenoid M1 also remains energized until vending is complete when relay M releases. The function of Geiger-Muller tube GM2-S is to reject tokens exhibiting radiation sufficient to penetrate an aluminium foil 14 which could arise with a spurious token. If GM2- S respons to radiation it energizes a relay S5 to disconnect relay M. The radio-active token may have radio-active material on one side only in which event the aluminium foil 14 may be dispensed with provided the token is inserted the correct way round to the device. Specification 990,256 is referred to.